Modifying a mower deck

[John Rumm]

Generally my mower works quite well, however it has difficulty with grass that is long and damp (not an unusual combination at the start of the mowing season in these parts!). This year was particularly bad since the ground was so water logged there was a substatial delay before the ground was firm enough to actually mow.

One of the problems being that my machine is designed to either cut and collect, or to mulch. It does not have the option to simply cut and drop. The net result is that it tries collecting, and then quickly clogs with wet grass, and then is by default trying to mulch. Even on its highest setting it soon bogs down trying to do that because all the cut grass is trapped in the deck.

Has anyone tried a (reversible) modification to a mower deck to open a "flap" in the side or back of it to allow grass to escape?

[Chris Hogg]

Depends on the design of the offtake for the cut grass into the grass collector. Mine is a spring-loaded flap, which is held open when the collecting bag is in place, but shuts in 'mulching mode'. It's not actually a mulching mower, and I get exactly the same problem as you when cutting longish wet grass. I have a short (8") bit of batten, about 1" square section, that I jam under the hinge-line of the flap, that holds it open but slightly angled downwards so the grass cuttings that get thrown out, backwards, don't fill my boots but are directed down to the ground.

[Harry Bloomfield]

John Rumm a écrit :

I have a tractor mower and what can be a very wet area to mow. I struggled with it for years - the tunnel constantly choking, backing up to the deck, then choking the blade and fan. The tunnel runs back from the deck, under the axle then feeds into a very large collector on the rear.

It already had a flap at the rear, so that if the collector is taken off, it drops the cut grass back on the ground.

I tried a home made panel to blank the front of the tunnel, that was better, but still it choked the fan and blade. Only when I removed the entire collection system did I acheive a reliable result.

The outlet from the deck is now completely open and it never chokes. The only problem I have is with the first cut of the season, where there are large clumps of cut grass. I allow that to dry, then go over it a second time, where it becomes better distributed.

[Brian Gaff]

Or an attached hair dryer on the front perhaps? :-)

Brian

[Tim Lamb]

In message , John Rumm writes

Yes but mine is a ride on:-)

One trick is use the mulch setting and then go back to pick up once the sun has taken out some of the moisture.

[The Natural Philosopher]

Mine came with one. First cut of the year I used it.

[John Rumm]

Mine has a pair of contra rotating blades, and the take off is a port in the top back of the deck in the middle. That is connected to a plastic tunnel (probably about 8" square) that then feeds through the back of the machine, out the back and into the grass box. So the blades naturally "throw" the grass in the direction of the outlet, and they are also shaped to create a fairly significant updraft (if you defeat the interlock that senses when the grass box is attached, then it will blow grass a good 12' out the back of the mower!)

Alas on mine I have tried similar - even if I defeat the grass box interlock (which I have done permanently with a batten tied under the cams that sense its presence), so it just discharges into thin air, it will still clog near the deck in the first 12" or so of grass tunnel.

[John Rumm]

Sounds similar to mine, except the tunnel rises and runs over the rear axle.

I notice that MTD have done a "diffuser" attachment for later models of my tractor, that seems to defeat the grass box interlock, and deflect the blown grass down onto the ground rather than allow it to flow backwards. However since mine will clog even when the grass box is not fitted, I don't expect that would actually help.

To be fair, that is something I have not tried - the tunnel is removable on mine (one can replace it with the mulching plug, which is a shaped plastic plug on the end of a long metal bar with some rubber straps that restrain the far end of the bar at the back of the mower). That would then leave the grass blowing straight out of the deck at the underside of the drivers foot well I guess.

If I could get the first cut done more easily[1] just dropping the grass back on the ground, then I have a towed sweeper which could do the collection.

[1] In the end I normally have to cut very slowly on the highest blade setting, stopping every time it sounds like the motor is bogging down and getting close to stalling, or disengaging the PTO to the blade, driving a bit to allow the accumulated grass to fall out of the deck and starting again. A much slower (and petrol thirsty) way to get it cut.

[John Rumm]

Now that's a bit of lateral thinking... I would need to tow a generator to run it though!

[Tim Lamb]

In message , John Rumm writes

That sounds like my Jonsered!

I fabricated a deflector from aluminium sheet to give a better spread and reduce the amount of clippings blown down my neck by the wind!

The plastic tunnel is retained by two spring hooks and the deflector is shaped to be trapped by the tunnel top and flange.

A short length of wood and a spring clip takes care of the grass box safety switch.

I found that regular use of the mulching device left rows of rotting trimmings which eventually damaged the grass. Altering the cutting route might have got round this but I'm mowing a strip 20m x 100m!

Yes. Back to fitting the mulcher!

[John Rumm]

Yup so is mine (sorry, should have mentioned that in the OP)... Its got a 36" deck on it.

Mine has not really got enough power (13 hp B&S) to mulch long wet grass

- its ok if mulching a dry lawn providing you do it at least twice a week.

[John Rumm]

Is it a flap right on the skirt of the deck?

[The Natural Philosopher]

I had similar power. I used to raise the deck to the max, cut, wait, cut again, wait a week, drop the deck a couple of inches, cut again.. THEN it was under controil and the mulcher would work

[The Natural Philosopher]

yes, But it could be removed to leave just a flappy metal guard on top of the deack sticking out over the slot for 'no mulch, spit it out sideways'

That is safety as much as anything. You don't want stuff flying up or your foot in the blades.

there's a good sort of picture of a typical way to do it.

shows a similar deck with the flappy METAL guard fitted.

Angle grinder and welder is a good starting point

[John Rumm]

It would be easier if I could get a higher max cut setting out of it - but I think about 90mm is the highest it will go. Perhaps I need a couple of larger diameter front wheels ;-)

[Brian Gaff]

I think with the rain we had yesterday evening, a large gas burner might be a better bet. Brian

[John Rumm]

MTD Lawnflite in this case...

I find if I mulch (which I do sometimes in the height of summer), then unless I mow twice a week, you get visible clippings left. Do it more often and it manages to "lose" them in the grass.

Doing about 60m x 60m (-minus the foot print of the house etc) here.

In effect yup...

I will have to have a look and see what happens if I take the whole tunnel out like Harry suggested above.

(probably a moot point for this year now, since I finally got it low enough at the weekend that it should be ok for the rest of the season - but there was a point after three hours of mowing and sweeping and mowing etc that I was almost ready to trade it in for a setup with built in brush collection!)